1. Field of the Invention
This invention relates to a solution to be optically treated, a method for forming an antireflection film, a method for pattern-plating and a method for manufacturing a thin film magnetic head using the pattern-plating method.
2. Related Art Statement
In a manufacturing method of a thin film magnetic head, normally, a second magnetic film serving as a top magnetic film is formed after a first magnetic film (bottom magnetic film), a gap film, an insulating film to support a coil film are formed on a wafer. Moreover, in the case of forming the second magnetic film, a plate-underfilm is formed on the whole surface of the wafer including the insulating film by a sputtering method, etc. Subsequently, a photoresist is applied on the surface of the plate-underfilm and is processed by a photolithography method to form a resist frame for forming the second magnetic film. Then, the second magnetic film is formed in the area surrounding the resist frame by an electroplating, etc. A film composed of the material constituting the second magnetic film is plated in an area beyond the resist frame, but it is removed.
In the second magnetic film-forming process, however, an exposing light in the photolithography process to form the resist frame is reflected at the surface of the insulating film and then, the reflected exposing light reaches an area beyond a photomask-defining area and exposes the photoresist around the area, resulting in the degradations of the pattern precision of the resist frame and the second magnetic precision.
The degradation of the pattern precision is conspicuous at the pole portion of the second magnetic film. The pole portion of the second magnetic film is opposed to the first magnetic film via the gap film. On the backward area from the pole portion is positioned the insulating film rising up with an inclination of a given angle from the surface of the gap film. The starting point of the rising up corresponds to a Throat Height zero point and the rising up angle corresponds to an Apex Angle.
The second magnetic film constitutes the pole portion parallel to the gap film and the first magnetic film up to the Throat Height zero point and then, rises up with an inclination of the Apex Angle toward the top surface of the insulating film from the Throat Height zero point.
Thus, in the case of fabricating the resist frame for forming the second magnetic film by the photolithography process, the photoresist stuck on the inclined portion at the Apex Angle of the insulating film toward the top surface must be exposed.
The plate-underfilm already stuck on the inclined portion reflects the exposing light. The part of the reflected exposing light reaches the pole portion. Thus, the exposing pattern of the pole portion is different from that of the photomask, resulting in the pattern destruction in a part of the resist frame corresponding to the pole portion.
The pattern destruction of the resist frame has difficulty in developing a recording density by narrowing a recording track width up to not more than 1.0 xcexcm.
Japanese Patent Application Kokai Hei 9-180127 (JP A 9-180127) discloses that before applying the photoresist as a mask for a top magnetic film, is formed the antireflection film, on which the photoresist frame is applied and the photoresist is exposed and developed to form the resistframe.
However, the conventional antireflection film is not dissolved in an alkaline developer to remove the resist frame. Accordingly, the antireflection is removed by an ashing method, etc. after the resist frame is removed by the alkaline developer, and then, the second magnetic film is formed, which results in the increase of the process number.
The antireflection film exists over the interior pattern surrounded by the resist frame. Then, the interior pattern has a pole portion area corresponding to the pole portion of the top magnetic film and a second yoke portion area corresponding to a yoke portion. Thus, the antireflection film has to be removed in both the pole portion area and the yoke portion area.
In the resist frame, however, the pole portion area has an extremely different opening area from that of the second yoke portion. Moreover, the pole portion tends to have the narrowed opening area of not more than 1 xcexcm for a high density recording. Accordingly, in the case of removing the antireflection film stuck on the interior pattern surrounded by the resist frame, the pole portion area has an extremely different etching rate from that of the second yoke portion, so that the pole portion area requires a longer etching time than the yoke portion area. As a result, the resist frame in the pole portion area is etched largely during the removing the antireflection film, resulting in the large distance of the resist frame. In other words, the antireflection film to narrow the width of the pole portion enlarges the distance of the resist frame because of the removing process of the film, resulting in having difficulty in narrowing the pole portion.
For explaining the conventional problems concretely, the method for the thin film magnetic head was described as above-mentioned, but the above problem is generally brought about in a pattern-plating method to plate a pattern on a surface of a body to be plated including an inclined portion.
It is an object of the present invention to provide a solution to be optically treated to form an antireflection film which resolves a photoresist developer without the intermixing with the photoresist and a method for producing the antireflection film using the solution.
It is another object of the present invention to provide a method for pattern-plating using the solution to be optically treated and a method for manufacturing a thin film magnetic head using the pattern-plating method.
It is still another object of the present invention to provide a method for manufacturing a thin film magnetic head in which a magnetic film is formed in a high precise pattern on an insulating film.
It is further object of the present invention to provide a method suitable for manufacturing a thin film magnetic head having a narrowed recording track width.
This invention relates to a solution to be optically treated comprising a cyclopentanone solvent, polymethylglutarimide and a light absorption dye.
In forming the antireflection film using the solution to be optically treated, the solution is applied onto an object body and thermally treated. Thereby, the antireflection film capable of dissolving in the alkaline developer which-is used in the photoresist developing can be obtained without the intermixing with the photoresist. The thermal treatment is preferably carried out at a temperature of 100-200xc2x0 C.
In the case of pattern-plating using the solution to be optically treated, the antireflection film is formed on a surface of a body to be plated including an inclined portion. Next, the photoresist is formed so as to cover the antireflection film.
Subsequently, a photolithography process to form a plated pattern on the body is carried out for the photoresist and the antireflection film to form a resist frame composed of the photoresist and the antireflection film.
Since the antireflection film capable of dissolving into the alkaline developer which is used on the photoresist developing is formed without the intermixing with the photoresist, in the case of forming the resist frame through the photolithography process, the photoresist and the antireflection film can be patterned at the same time so as to have their same pattern. Moreover, since in the photolithography process, another process to remove the antireflection film is not required, the photolithography process can be simplified.
The solution to be optically treated and the pattern-plating method exhibit conspicuous operation/working effects. As is well known, the thin film magnetic head has a slider and a thin film magnetic head element. The slider has an air bearing surface in the opposing side to a recording medium. The thin film magnetic head element has a first magnetic film, a coil film, an insulating film, a gap film and a second magnetic film, which are supported by the slider.
The first magnetic film has a first pole portion and a first yoke portion. The first pole portion is composed of the end portion of the first magnetic film in the side of the air bearing surface. The first yoke portion is connected to the first pole portion continuously and be extended backward from the air bearing surface.
The gap film is formed at least on a surface of the first pole portion. The insulating film supports the coil film, being positioned on the first yoke portion and has a rising inclined portion in the side of the air bearing surface.
The second magnetic film has a second pole portion and a second yoke portion. The second pole portion is opposite to the first pole portion via the gap film. The second yoke portion is provided on the insulating film, being connected to the second pole portion continuously and is coupled to the first yoke portion backward.
In manufacturing the thin film magnetic head, after forming the first magnetic film, the gap film, the coil film and the insulating film and before forming the second magnetic film, a plate-underfilm for the second magnetic film is formed on the surface of the insulating film including the inclined portion and then, an antireflection film is formed on the plate-underfilm formed on the surface of the insulating film including the inclined portion. The antireflection film is formed by applying the solution to be optically treated in which the PMGI and the light absorption dye are dissolved in the cyclopentanone solvent.
Subsequently, a photoresist is formed so as to cover the antireflection film. A photolithography process for the second magnetic film is carried out for the photoresist and the antireflection film to form a resist frame composed of the photoresist and the antireflection film. Then, the second magnetic film is formed in the pattern area surrounded by the resist frame.
Since the rising inclined portion of the insulating film has the antireflection film, in forming the resist frame by the photolithography process for the second magnetic film, the exposing light is almost never reflected at the inclined portion of the insulating film. Thus, particularly, the exposed pattern of the photoresist to define the second pole portion in the second magnetic film is almost determined by the exposing pattern of a photomask and thereby, the resist frame pattern corresponding to the second pole portion can be formed precisely. Consequently, according to the present invention, the second pole portion can be formed in a precise pattern. Moreover, since the resist frame pattern corresponding to the second pole portion can be formed precisely, the thin film magnetic head having a narrowed recording track width can be manufactured.
Moreover, since the solution to be optically treated can form the antireflection film which dissolves in the alkaline developer which is used in the photoresist developing without the intermixing with the photoresist, in the forming the resist frame by the photolithography process, the photoresist and the antireflection film can be patterned at the same time so as to have their same pattern. Another process to remove the antireflection film is not required. Consequently, the photolithography can be simplified.
Furthermore, the antireflection film can be removed with the photoresist in the developing process, the process to remove only the antireflection film is not required. Thus, the degradation of the pattern precision of the resist frame and the decrease of the height of the resist frame, due to the difference in the etching rates between the second yoke portion and the second pole portion, does not occur. Consequently, the second pole portion and the second yoke portion can be formed in their precise patterns.
This invention may be applied for a self-alignment type (herein-after, called as a xe2x80x9cSA typexe2x80x9d) thin film magnetic head. In the SA type thin film magnetic head, the insulating film includes a first insulating film and a second insulating film. The first insulating film supports the coil film. The second insulating film is formed on the base portion of the first insulating film in the side of the air bearing surface and define the Throat Height zero point.
Moreover, in the second magnetic film, the second yoke portion is positioned on the first insulating film, its one end portion being connected to the second pole portion continuously, its other one end being coupled to the first yoke portion.
In manufacturing the SA type thin film magnetic head, after forming the first magnetic head, the gap film and before forming the coil film, the first insulating film, the second magnetic film, the second insulating film is formed on the gap film.
Next, a plate-underfilm is formed on the gap film and the second insulating film. Then, an antireflection is formed on the plate-underfilm on the second insulating film. The antireflection film is formed by applying the solution to be optically treated in which the PMGI and the light absorption dye are dissolved in the cyclopentanone solvent.
Subsequently, a photoresist is formed so as to cover the antireflection film. Then, a photolithography process for the second magnetic film is carried out for the photoresist and the antireflection film to form a resist frame composed of the photoresist and the antireflection film.
Next, the second pole portion is formed in the pattern surrounded by the resistframe. Thereafter, the first insulating film and the coil film and the second yoke portion are formed.
Since the antireflection film is positioned on the second insulating film in the side of the air bearing surface, in forming the resist frame by the photolithography process for forming the second pole portion in the second magnetic film, an exposing light is almost never reflected at the inclined portion of the second insulating film. Accordingly, the exposed pattern of the photoresist covering the second pole portion is almost defined by the exposing pattern of a photomask and thereby, the photoresist pattern corresponding to the second pole portion can be formed high precisely. As a result, the second pole portion can be formed in a high precise pattern. Moreover, since the resist frame pattern corresponding to the second pole portion can be formed high precisely, the thin film magnetic head having a narrowed recording width can be provided.
Furthermore, since the solution to be optically treated can form the antireflection film which dissolves in an alkaline developer which is used in the photoresist developing, in forming the resist frame by the photolithography process, the photoresist and the antireflection film can be patterned at the same time so as to have their same pattern. Another process to remove the antireflection film is not required. Thus, the photolithography process can be simplified.
Moreover, since the antireflection film is removed with the photoresist, the process to remove only the antireflection film is not required. Accordingly, the degradation of the pattern precision of the resist frame and the decrease of the height of the resist frame, due to the difference in the etching rate between the second yoke portion and the second pole portion, are prevented. Consequently, the second pole portion and the second yoke portion can be formed in their precise patterns.
The other objects, configurations and advantages will be explained in detail, with reference to the attaching drawings in embodiments.